P: Photos incorrectly considered as "changed" by republishing and smart collections

Excellent!

I verified that your steps work around the particular instance of the problem described here: https://feedback.photoshop.com/photoshop_family/topics/modified-to-republish-problem?topic-reply-lis...

For others reading this who aren't as familiar with LR commands, the steps are:

1. In the Catalog panel on the left, click on All Photographs.

2. Do Edit > Select All.

3. Do Metadata > Save Metadata To File.

4. Do Metadata > Read Metadata From File.

5. In the Publish Services panel, click on a published collection that contains Modified Photos To Re-Publish.

6 Right-click one of the select pics and do Mark As Up-To-Date.

7. Repeat steps 5-6 for every published collection affected by the bug.

I found a way to fix this issue in all the photos that I have in a Lightroom Catalog. My Lightroom version is CC 2015.7

Follow these steps:

1) Select all your Pictures in your Catalog.
2) Save metadata to file
3) Read metadata from file 
4) Go to your published services Folders and select all the pictures
5) Mark all the pictures as up-to-date.

After doing these steps published folders work properly. No more random pictures appear under "Modified Photos to Re-Publish". 


Enjoy Lightroom again!

Thanks a lot for your support!

I just posted a precise recipe for reproducing the bug and updated the original post with a link to the recipe. This is often required to get Adobe to add the bug to their bug-tracking, but it doesn't guarantee a fix.

At least some instances of this bug are caused by the new develop settings added by CC 2015.6 for the Guided Upright tool. When 2015.6 or later first renders a photo at 1:1 zoom that had been imported by 2015.5 or earlier, it adds those develop settings before rendering. Then it compares those develop settings with the old, notices they are different, and marks the photo to be republished (incorrectly).

Here's a recipe for reproducing the bug:

1. In CC 2015.5, create a new catalog with Catalog Settings > File Handling > Standard Preview Size = 1440 pixels. Uncheck the option Catalog Settings > Metadata > Automatically Write Changes Into XMP.

2. Make a folder with 50 copies of this 5472 x 3648 raw file: https://dl.dropboxusercontent.com/u/21811200/DSC05456copy1.ARW

3. Import the folder into LR and wait until the standard previews have built.

4. Set up the Flickr publish service with default settings, except Resize To Fit: Width & Height = 1000 x 1000 (to make the uploads go faster).

5. Make a Flickr publish album containing all 50 pics and publish it.

6. Exit LR CC 2015.5 and start LR CC 2015.7 on the same catalog.

7. Using the plugin SDK, verify that all of the photos have the develop setting UprightVersion == nil (this is one of the settings added for Guided Upright in 2015.6):

        

This plugin is handy for examining the internal metadata and develop settings of a photo as exposed by the plugin SDK.

8. While viewing the published Flickr album in grid view, select one of the photos, go to Loupe, and then zoom 1:1.  The photo will show up in Modified Photos To Re-Publish. And often the next photo in grid view will also show up, presumably because of LR's pre-rendering policy.

9. Repeat step 8 a number of times.

10. Verify that the photos that appear in Modified Photos To Re-Publish are exactly those with the develop setting UprightVersion ~= nil:

        
        
----------------------------------------------------------------------

Examining the before and after develop settings of a photo, it's exactly the settings added for the Guided Upright tool that appear after the 1:1 zoom but not before:

PerspectiveX = 0, 
PerspectiveY = 0,
UprightCenterMode = 0, 
UprightCenterNormX = 0.5, 
UprightCenterNormY = 0.5, 
UprightFocalLength35mm = 35, 
UprightFocalMode = 0, 
UprightPreview = false, 
UprightTransformCount = 6, 
UprightVersion = 151388160, 

It appears that when
a photo imported into the catalog by CC 2015.5 is zoomed 1:1 for the first time
in CC 2015.7, LR adds the Upright settings with default values to the develop
settings, then it renders the photo.  It
then compares the new develop settings with the old, notices that the Upright
settings are different, and marks the photo for republishing.

 The fix is to treat
a nil value for those settings the same as the default settings, thus avoiding the spurious conclusion that the photo has changed.

That's exactly how I read the API documentation on this callback:

It allows the plug-in to specify which metadata should be considered when Lightroom determines whether an existing photo should be moved to the "Modified Photos to Re-Publish" status.

No develop settings mentioned here. That means that any publish service will suffer from this (d)ef(f)ect.

I think we now can hand this bug to Adobe on a a silver platter, can't we?

"The publishServiceProvider.metadataThatTriggersRepublish()  function returns { default = true}, i.e. any metadata change will trigger re-publish. I think, most of the Publish plugin will use that setting."

I'm not expert on implementing publish services, but I think that changes to Develop settings always trigger a republish, regardless of what that function returns.  I say that because this is what all of Friedl's publishing services show:


I think Friedl designed the LR SDK's publish-service architecture, under contract to Adobe, so he would know (only 85% confident about that).

That sounds reasonable and it explain why I don't see this effect when I zoom-in photos that were last edited w/ the latest Lr version.

I using the Photo StatLr plugin (upload to Synolgy Photo Station) which was written by me.

The publishServiceProvider.metadataThatTriggersRepublish()  function returns { default = true}, i.e. any metadata change will trigger re-publish. I think, most of the Publish plugin will use that setting.

Interesting, these are the only differences.  The Develop settings are for the Guided Upright tool, which was introduced in CC 2015.6 / 6.6.    Here's what may be happening:

1. You zoom-in on a photo last edited in CC 2015.5 / 6.5.   

2. LR decides it needs to render the photo, and as part of that, it adds the develop settings for Guided Upright (at their default values).

3. It compares the new develop settings with the old, sees that they're different, and marks the photo for republishing.  (Though publishing services can define which metadata fields should be considered when decided if a photo should be republished, I believe that changes to develop settings always trigger a republish.)

A potential fix is to make the comparison of old and new develop settings smarter, so that a nil-valued (missing) Guided Upright setting is considered the same as the default value, and thus "no change".

Which publish services have you observed with this problem?

That's a cool tool!

Results:
http://messmer-online.de/Metadata-Before-After-Zoom.zip

Metadata Before and After differ a lot in the Delevop section. But if you sort the Develop section, you'll find that the only difference are the following new items in the 'After' version:

PerspectiveX = 0,
PerspectiveY = 0,
UprightCenterMode = 0,
UprightCenterNormX = 0.5,
UprightCenterNormY = 0.5,
UprightFocalLength35mm = 35,
UprightFocalMode = 0,
UprightFourSegmentsCount = 0,
UprightPreview = false,
UprightTransformCount = 6,
UprightVersion = 151388160, 

I did not even enter the Develop mode!